Christened Michael Ryan Pritchard on May 4th, 1972, Mike was born in Berkeley California. His mother was an empoverished herion addict who quickly put him up for adoption. Mike was adopted by a Native American woman and her Caucasian husband. The couple divorced when Mike was seven, and he divided his time between them for a while, finally settling with his adoptive mom.

In fifth grade, Mike met his future bandmate, Billie Joe Armstrong. Sparked by a mutual love of music and desire to play guitar, their friendship developed quickly. When he was 15, Mike's adoptive mother moved away to Santa Rosa. Not wishing to move, he made an agreement with Billie's mother and rented a room at their house. He held various jobs during this time, to pay the rent & finance his musical interest.

Billie and Mike learned to play guitar and, got their first gig at Rod's Hickory Pit in 1987, under the name "Sweet Children". Since Mike was a better rhythm guitarist than lead, he decided to play bass. From that point onward, the two friends played shows whenever possible. During Mike's sophmore year of high school, he moved to a West Oakland squat with Billie, where they jammed with many different bands. Green Day was soon created, and the two of then began to take it very seriously.

In August of 1996, Mike Dirnt married his girlfriend Anastasia. A girl was born to the couple in April 1997, they named her Estelle-Desiree. Unfortunately, due to the pressures of touring with Green Day, Mike and Anastasia divoriced. They remain on good terms, so Mike visits his daughter whenever possible.